Ganahl



March 3, 1964 GANAHL HYDRAULIC PISTON MACHINES 2 Sheets-Sheet 1 FiledSept. 24, 1962 March 3, 1964 A, GANAHL 3,123,013

HYDRAULIC PISTON MACHINES Filed Sept. 24, 1962 2 Sheets-Sheet 2 UnitedStates Patent 3,123,013 HYDRAULIC PISTON MACHINES Aifred Ganahl, Kloten,Zurich, Switzerland, assignor to Aktiengesellschaft Ernest H. FischersSiihne, Dottikon, Aargau, Switzerland Filed Sept. 24, 1962, Ser. No.225,807 Claims. (Cl. 103-161) Hydraulic pressure pumps and motors arerequired to convey appropriate pressure fluids by displacing them fromenclosed chambers or to supply such pressure fluids to such chambers forconversion into mechanical power. Constructions have accordingly beendevised in which the piston stroke can be varied to control the sweptvolumes delivered per unit of time. Devices of this kind have becomequite popular and are technically satisfactory, but the controlledstroke feature makes the transmission elements of such machinesexpensive since the bearing elements which transmit the hydraulic forcesfrom the displacing system to the rotating system must themselves beadjusted. There has long been a requirement for systems which will varythe effective swept volume but which are free from the complications ofthe controlled stroke feature. A number of suggestions have been made.For instance, it is known to vary the volume of high-pressure pumps byarranging for the valve opening and closing times to be shifted in timerelatively to piston stroke-the so-called sequence control method. It isalso known to construct the swept volume from a number of displacementelements, the phase of which relatively to the transmissions displacingthem can be shiftedi.e., different volumes can be delivered. To date,however, it has proved impossible to construct pumps and motors forpressures above 200 atmospheres absolute which will operate controlsystems of this kind and which are of reliability comparable to thecorventional stroke-controlled pressure pumps.

This invention helps to solve the problem. According to the invention,although the complete machine is of simple construction two controlfeatures are provided control by phase sequence, and control byvariation of the swept volume by phase differences between two displacement elements operating in a communicating chamher. The combinationof these two features, each of which is known per se, enables variationof delivery direction to be combined with the advantage of control ofthe swept volume. Stroke-controlled pumps in which the piston stroke canbe controlled in the driving mechanism operate to either handi.e., ineither direction of conveyance. If the displacement chamber were to becontrolled by the difference between the phases of two elements, therewould be no possibility of changing the direction of rotation in thisway, since the physical relationship of the resultant strokes relativelyto the control surface remains constant. However, this difiiculty isovercome by the combination according to the invention of phase sequencecontrol with displacement control, and a pump or a motor can be devisedwithout any extra outlay but having the controllability ofstroke-regulated machines but being simpler in construction and cheaperto construct than stroke-regulated machines.

For a better understanding of the invention and to show how the same maybe carried into effect, reference may now be made to the accompanyingdrawing wherein:

FIG. 1 is a longitudinal section through a radial piston machineconstructed as a pump;

FIG. 2 is a cross-section taken along the line IIII of FIG. 1;

FIG. 3 is a longitudinal section through a radial piston machineconstructed as an infinitely variable transmission, and

3,123,913 Patented Mar. 3, 1964 FIG. 4 is a longitudinal section througha two-stage piston of the radial piston machine.

The pump illustrated in FIG. 1 comprises a rotor 1 which is driven by ashaft 2 and which is centered on a control member (control surface) 3rigidly secured to a casing 4 closed by a cover 5. Two-piece pistons 6,6' engage by way of pivots 7 and rollers 8 with cams 9 and 10. Throughthe agency of hand wheels 13, gearing 11 and worms 12, the cams 9, 10can be adjusted angularly. The delivery chambers of the pistons 6 areinterconnected by a duct 14. The control surface 3 has four ducts 15, 15which are interconnected by cross-connections i6, 16 and which extend toinlet or outlet apertures 17 and 17. Cylinder chambers 18 have throughconnections to one another through ducts 1?. The fluid is supplied andremoved, and the control is eifected, by way of perforations 20, 29' inthe control surface 3.

The shape of the two cams 9 and 10 can be imagined as the shape arisingout of one complete sinusoidal oscillation being superimposed upon acircle. The two cams 9 and 10 are ofltset by from one another and so thepistons 6, 6' move to opposite hands, with the result that the fluid inthe compression chamber performs merely an oscillatory motion. When thetwo cams 9 and 10 are in the same position so that they overlap, the twopistons perform a parallel movement to provide maximum delivery. Toreverse the flow of liquid, the two cams 9 and 19 are rotated togetherthrough 90 so that their position relatively to the perforations orapertures 20 and 26' is so altered that they change over from the intakeside to the delivery side. The top cylinder chambers 18 of the steppedpistons 6 and 6 are interconnected by a ring duct 19. Since the totalvolume in these chambers always remains the same, the liquid containedin such chambers applies a restoring force to the pistons in addition tocentrifugal force which is also operative radially.

FIG. 3 illustrates a radial piston machine constructed as transmission.The construction of the pump is identical to the constructionhereinbefore described, but the ducts 15 and 15' extend direcly to themotor which is similar in construction to the pump except that thesecond set of parallel-guided pistons is omitted. In this embodiment thefluid moves in a closed circuit from the pump to the motor and back.Motor speed is controlled by controlling the pump in the mannerhereinbefore described, and the direction of rotation of the motor isreversed by reversing the direction of the liquid flow. The speed, powerand torque of the motor can be adjusted by adjustment of the cam 10'.

FIG. 4 illustrates the two-piece stepped piston 6 and 6 with its pivot 7and roller 8. A connecting element 21 is loaded by springs 22-shown hereas spring washers to ensure that the piston 6 is not subjected to thevery high pressures associated with the passage of the piston 6 over theclosed parts of the control surface 3. The force of the springs 22 isadapted to the required maximum delivery pressure absorbing the highstresses reduces the wear.

What I claimed is:

1. A fluid power device comprising, in combination, a housing; a rotorrotatably mounted in said housing and formed with a pair of axiallyspaced radial bores; a piston reciprocable longitudinally of each borein operative association with pressure fluid in the respective bore; astationary control member having angularly displaced fluid inlet andoutlet passages; duct means connecting each bore to passage means insaid control member connected to one of said passages; a pair of angularcontrol cams in said housing substantially concentric with said rotorand each having a substantially circular outer periphery and asinusoidal inner periphery, each cam being radially aligned with arespective piston; a cam follower connected to the outer end of eachpiston and engaged with the inner periphery of the associated cam, forreciprocation of the pistons during relative rotation of said rotor andsaid cam; and a pair of independently actuable adjusting means eachoperative to eflect angular adjustment of a respective cam independentlyof the other cam to select the absolute phase relation of the associatedrespective cam to said control member and the relative phase relation ofsaid cams to each other.

2. A fluid power device, as claimed in claim 1, in which said radialcores are disposed in a common radial plane of said rotor; each bore ofsaid pair being connected to the same passage means in said controlmember; whereby, by relative angular adjustment of the respective cams,the time relation of the displacement of the pair of pistons may beselected at will.

3. A fluid power device, as claimed in claim 2, in which said cams aresubstantially identical and each cam eflects two reciprocations of itsrespective piston during each revolution of said rotor.

4. A fluid power device, as claimed in claim 1, including resilientmeans interconnecting each cam follower to its associated piston to evenout the compression peaks arising during operation of said device.

5. A fluid power device, as claimed in claim 4, in which piston, thehead of said element being disposed in said recess; and compressionspring means disposed between the head of said element and the innerwall of said recess and between the outer surface of said support inherend and the outer end of the associated piston.

References Cited in the file of this patent UNITED STATES PATENTS2,872,875 Mergen et al Feb. 10, 1959 Hotter Feb. 7, 1950 V

1. A FLUID POWER DEVICE COMPRISING, IN COMBINATION, A HOUSING; A ROTORROTATABLY MOUNTED IN SAID HOUSING AND FORMED WITH A PAIR OF AXIALLYSPACED RADIAL BORES; A PISTON RECIPROCABLE LONGITUDINALLY OF EACH BOREIN OPERATIVE ASSOCIATION WITH PRESSURE FLUID IN THE RESPECTIVE BORE; ASTATIONARY CONTROL MEMBER HAVING ANGULARLY DISPLACED FLUID INLET ANDOUTLET PASSAGES; DUCT MEANS CONNECTING EACH BORE TO PASSAGE MEANS INSAID CONTROL MEMBER CONNECTED TO ONE OF SAID PASSAGES; A PAIR OF ANGULARCONTROL CAMS IN SAID HOUSING SUBSTANTIALLY CONCENTRIC WITH SAID ROTORAND EACH HAVING A SUBSTANTIALLY CIRCULAR OUTER PERIPHERY AND ASINUSOIDAL INNER PERIPHERY, EACH CAM BEING RADIALLY ALIGNED WITH ARESPECTIVE PISTON; A CAM FOLLOWER CONNECTED TO THE OUTER END OF EACHPISTON AND ENGAGED WITH THE INNER PERIPHERY OF THE ASSOCIATED CAM, FORRECIPROCATION OF THE PISTONS DURING RELATIVE ROTATION OF SAID ROTOR ANDSAID CAM; AND A PAIR OF INDEPENDENTLY ACTUABLE ADJUSTING MEANS EACHOPERATIVE TO EFFECT ANGULAR ADJUSTMENT OF A RESPECTIVE CAM INDEPENDENTLYOF THE OTHER CAM TO SELECT THE ABSOLUTE PHASE RELATION OF THE ASSOCIATEDRESPECTIVE CAM TO SAID CONTROL MEMBER AND THE RELATIVE PHASE RELATION OFSAID CAMS TO EACH OTHER.